Question: $\dfrac{9}{4} - \dfrac{1}{10} = {?}$
Answer: $ = {\dfrac{9 \times 5}{4 \times 5}} - {\dfrac{1 \times 2}{10 \times 2}} $ $ = {\dfrac{45}{20}} - {\dfrac{2}{20}} $ $ = \dfrac{{45} - {2}}{20} $ $ = \dfrac{43}{20}$